Astrobiologist Chris McKay travels to the world's harshest landscapes to search for clues about the potential for life on other planets. He's endured clouds of mosquitoes in the Siberian permafrost and prepared for polar bear attacks in the Canadian Arctic.

McKay calls his favorite field sites — picked for both scientific and aesthetic reasons — the “seven wonders of the Mars analog world.” But his search to understand possible alien ecosystems isn’t limited to the Red Planet. His research trips have taken him to Saturn’s moons and the volcanoes of Venus — or at least, as close as he can get without leaving terra firma.